What can you hear when the screen goes dark? Does the screen come back on or does it remain dark?
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DaveSep 18 '13 at 14:53

It remains dark. And i hear something bzzzzz when it's going to dark out.
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KetsSep 18 '13 at 15:05

One of my friends came to me with this exact same issue and the exact same laptop a couple days ago. I wasn't able to help him. I think there is a bad batch of back lights in this models screen. The issue does not seem to originate from software at all.
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Jason BristolSep 18 '13 at 17:04

Do you have the Power Saver option selected on the Laptop's Power Options?
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YassSep 18 '13 at 17:33

Boot into the BIOS and see if the screen still goes dark after X amount of time. You may be able to eliminate the OS causing this issue.
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YiweiGSep 18 '13 at 18:28